Kelly Clarkson has been dating boyfriend Brandon Blackstock since late last year, but the singer admits she's long known they're "so getting married" some day.

First introduced to Blackstock years ago when he worked as Rascal Flatts' tour manager, Clarkson, 30, tells Ryan Seacrest her man was in another relationship at the time, but she refused to let him get away. "We were just in a room together, and then he came up and said he was from the same hometown as me and I was like, 'oh, we're so getting married' -- I was so that girl," Clarkson recalled during an interview on Seacrest's KIIS-FM morning radio show. "When he became single, I was on the prowl."

In the time since Us Weekly broke news of their relationship in March, Clarkson has became more open about her unique bond with the Nashville-based talent manager, 35, who is the stepson of Clarkson's pal Reba McEntire. One major plus to dating Blackstock? He helps spark creativity in the singer, who will release a greatest hits album in November. (To see a photo of Blackstock, click here.)

"Once you finally fall in love with someone and you are so comfortable with them, it makes you more comfortable in your skin. It makes you comfortable as an artist and it makes you more confident," reasons Clarkson. "I'm completely head over heels for him, he knows that."